Stabilized vacuum-tube lighting system



Dec. 17, 1929. L. L. BECK 1,739,498

STABILIZED VACUUM TUBE LIGHTING SYSTEM Filed June 2, 1926 a I w o 2. i; 3 o

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' LE6 L; BECK, OF LINDEN, NEW JERSEY STABILIZED VACUUM-TUBE LIGHTING SYSTEM Application filed June 2, 1926. Serial No. 113,145.

This invention relates to vacuum tube lighting systems in which a transparent envelope containing gas, such as neon, at relatively low pressure is caused to glow and radiate light by the passage of an electric cur- I rent therethrough and more particularly to a system such as described in which the power utilized for operation is drawn from an ordinary commercial outlet, such, for example, as

. an outlet supplying alternating current of 60 cycles frequency at 110 volts. It is an object of this invention to provide an improved system of the class described and more particularly to provide astabilized system for which the various elements may be calculated and designed with'the certainty that when built and installed they will operate with the designed characteristics or with It is a further object of this invention to provide a new and improvedt pe of transformer for use in an electrical circuit which includes 'a device having inherent negative resistance characteristics and which may be calculated and designed and the performance of which may be accurately predicted regardless of the conditions under which the trans former required to be operated.

Still other objects of my invention will be apparent from the specification.

he features of novelty which I believe to r be characteristic of my invention are pointed out with particularity in the appendedcla-ims. My invention itself, however, both as to its underlying principles and as to its practical application will best be .understood by reference to the specification and accompanying drawing, in which:

Figure 1 is a diagrammatic view of a lighting system according to my invention;

Figure 2 is a sectional elevation of a transformer according to my invention; and

Figure 3 is ure 2.

Lights of the class described generally comprise an evacuated envelope containing a gas such as neon at relatively low pressure. The envelope is usually in the form of a relatively long tube and .is frequently bent into the very little deviation vtherefrom regardless of variations in the position of component parts. f

form of words, special designs andthe like and is provided with electrodes usually in ternal for the passage of current through the gas.

A relatively high voltage is required for the operation of the usual typeof tube. This voltage may vary between 10,000 and 15,000 volts and of course is not available from commercial power outlets. Therefore itis neces sary to interpose" somesort of converting e0 means, usually atransformer, between the commercial power outlet and the vacuum tube lightfor stepping the voltage up to the valuerequired For reasons with which I am not here con- 05 cerned but which are due primarily to the fact that such lights have inherent negative resistance characteristics it is desirable to operate the lights at a relatively low power actor as described and claimed in my application filed concurrently herewith entitled Vacuum tube-lighting system and this is preferably done by utilizing a high leakage transformer having a primary adapted to be .connected to the ordinary 110 volt, 60 cycle or other available source of supply and a secondary adapted to furnish the high voltage required for the light. In these high leakage transformers as usually constructed the magnetic flux produced by the windings is not confined entirely in a magnetic core, but a relatively large proportion escapes into the surrounding space.

As these lighting systems are usually used for advertising purposes, they are frequently mounted outdoors ex osed to the weather and for this reason the tu es are usually mounted 1 upon a support preferably in the form of a box or box-like structure of metal, frequently sheet, iron. The tubes are mounted in such a way that the main portionof the tube is outside of or in front of the supporting plate.

. The electrode portions however; are in back a section on lines 33'of Figg of or within the support. The, transformer" is likewise carried with the support and preferably so that the highyoltage leads are never brought outside of the box thereby avoiding accident and insuring uninterrupted operation of the system. 7

It has been found however, that in the past 1 such systems differed widely in their actual operating characteristics from the operating characteristics for which they were designed. The power drawn by the sign frequently varied Widely from the calculated amount, the voltage also varied and the power factor of the transformer might vary so that it was not possible to predict from design data what the performance of a system would be in actual operation.

I have discovered that the difliculty arose from the fact that the transformers being of a high reactance type and having high leakage were surrounded by a magnetic flux field which was not confined to the transformer core. The position of the transformer within a boX-like support therefore had a very considerable effect upon the operation of the system where the walls of the box were composed of magnetic conducting material. For instance if the transformer were placed adjacent to a sheet iron support, or other magnetic conducting material, the reluctance of the flux leakage path would be greatly decreased and the fluxfdistribution for which the transformer was designed would be materially affected, thereby producing a different secondary voltage; a different primary current and even a different power factor on the primary side, and as a result of this the same transformer and light would have widely different performance characteristics in accordancewith the location of'the transformer with respect to the support or other magnetic conducting body in any particular instance.

I have overcome this by enclosing the transformer in a shield preferably of metal, such as iron, and so constructed and arranged that the flux produced by the windings is substantially entirely confined therein. It will be unv derstood of course that the performance of a high leakage transformer will be considerably affected by placing it in such a shield. However, the effect will always be the same and may be measured and corrected for very I easily in the design; that is to say, itr'nay be i found for instance that it is necessary to add ten turns to the secondary winding to compensate for the effect of the shield. The figures given are merely arbitrary by way of example, and have no significance. In brief, the iron casing or shield picks up the stray leakage flux, which causes eddy currents in the iron of the shield, and so gives a definite and known loss of power and potential, which, by reason of the fact that it is de'finite, enables the performance ofthe transformer to be controlled.

Referring now to Fi ure 1, 1 designates the tubular envelope of t e vacuum tube light containing gas such as neon at low pressure and having bulb portions 2 carrying electrodes 3 mounted on lead-in wires 4 passing through a press 5. The tube 1 preferably The transformer itself may consist for example of a. winding 11, a second winding 12, one of which is the primary and the other the secondary, mounted for example on leg 14 of core 13 and separated by a suitable spacing element 17 which may be of insulating material. The core and coil assembly is mounted upon a base plate 17 of shielding material and provided with a cover 16 of shielding material provided with openings through which the leads may be brought out but otherwise completely encasing the trans-, former within a shield. The cover 16 and base plate 17 may satisfactorily be made of sheet iron stamped or otherwise formed to the desired shape.

The principal advantage of building ;the supporting structure or box of sheet iron or the like is its strength and comparativel low cost. But, obviously, the support might be made of sheet zinc or other non-ferrous metal, or even of wood. In such case the problem of instability in the transformer performance would not obtain so far as the sign structureper se is-concerned. But there would still remain the need for protecting the transformer from the influence of extraneous ferrous objects. Such signs are frequently steel or iron in their structures; a sign may be mounted directly on an iron cornice or store front. Iron braces or a steel structure erected to carry the sign may introduce disturbing influences. My shield is adapted to protect the transformer from all of these.

It is to be understood that I am not here concerned with the specific details of the coils and core assembly or with other arrangement to provide for high leakage. It will therefore be understood that any suitable arrangement such as a magnetic shunt or the like may be used to produce the high leakage desired. I

Figure 4 represents in diagrammatic form a source of electric current of predetermined potential 20 connected to a high leak transformer 21 in aniron casing 22, and a sign tube 23.

While I have shown and described the preferred form of my invention it is to be understood that I am not limited thereto and that modifications and changes may be made withinvention as will be understood by those skilled in the art.

What I claim is:

' 1. In combination, a source of electric current of predetermined potential, a high leak compensated transformer and a aseous electric discharge device, the trans ormer being enclosed in an iron casing, the iron casing serving to ick up magnetic flux and, transform such ux into energy losses which losses are definite whereby the performance of the transformer is controlled and determined, said compensation being substantially equivalent to the loss of potential occasioned by the said energy losses.

2, In a luminous tube sign, in combination, a tube containing ionizable gas, a high leak compensated transformer adapted to deliver high potential electric current to said tube, and a source of electric current of predetermined potential, said transformer being provided with an iron casing, the casing being 7 adapted to ick up magnetic flux and transform such ux into energy losses which losses are definite, the windings of the transformer being adjusted tocompensate for loss of potential caused by the said energy losses and the transformer being thereby adapted to deliver operative potential to the tube uninfluenced by magnetic disturbances outside the casing of the transformer. I

3. In a luminous tube sign, in combination, a tube containing ionizable gas, a high leak compensated transformer adapted to deliver high potential electric current to said tube, a sourceof electric current of predetermined potential and an iron support, the said tube and transformer being supported upon the said iron support, the transformerbelngprovided with an iron casing, the casing being adaptedto pick up magnetic fluxand transform such flux into energy losses whichl'osses are definite, the windings of the transformer being adjusted to compensate for loss of po tential caused by-the said, energy losses and the transformer being thereby adapted to deliver operative potential to the tube uninfluenced by. the said iron support. In testimony whereof, I have hereunto set my hand this 21 day of May, 1926.

LEO L. BECK. 

